Production of motor fuels



Patented Jamil, 1944 2,339,106 PRODUCTION OF MOTOR. FUELS Mathias Pier,Heidelberg,

Mannheim, Germany;

erty Custodian N Drawing. Application No. 359,230, In Gem 1 Claim.

The present invention relates to a process for the production of motorfuels.

It is known that aliphatic hydrocarbon mixtures, boiling mainly withinthe boiling range of middle oils, 1. e., between about 200 and about 3250., can be converted into low-boiling hydrocarbon oils of the gasolinetype by cracking them in the presence of stationary catalysts. In thisprocess, however, the catalyst loses efiiciency already after a shortuse owing to the deposition of high molecular weight polymerizationproducts to such an extent that it must be reactivated or regenerated bythe removal of these products. An excessive formation of undesirabledeposits upon the catalyst can only be avoided by performing thereactivation of the catalyst after a short use for the reaction desired.It was only by the development of the catalytic destructivehydrogenation in the gas phase that it hecome possible to convert higherboiling hydrocarbon oils into low-boiling ones, practically without thecatalysts sufiering a decrease of activity. jnlike the ordinarycatalytic cracking process, however, the destructive hydrogenation mustbe carried out in apparatus capable of withstanding high pressures;besides, since hy drogen is consumed in the reaction provision must bemade for its production.

We have now found that aliphatic hydrocarbon oils, substantially of themiddle oil boiling range, can be cracked under such reaction conditionsthat, though hydrogen is present, it is not consumed, that high pressureis not needed, that the catalyst remains active for remarkably longperiods oi time and that gaseous hydrocarbons I are formed to acomparatively slight extent only.

For this purpose, the initial materials, while in a vaporous state, arepassed over one or more of the oxides of the metals of the 2nd to the6th group of the periodic system, at temperatures between 420 and 560C., together with hydrogen, under a total pressure between about 3 andabout atmospheres and a hydrogen partial pressure amounting to at least25 per cent of the total pressure, but to no more than half thereof, andthe gases containing hydrogen leaving the reaction space are returnedthereto, without adding fresh hydrogen, in an amount of from about 0.3to about 2 cubic meters, preferably from 0.5 to 0.9 cubic meter, perkilogram of initial materlal.

As initial materials may be mentioned middle oils containing at leastper cent, preferably from to per cent or more of parafflnichydrocarbons. for example middle oils from paraffinand Ernst Donath.

vested In the Allen Prop- October 1, 1940, Serial any October 4, 1939base mineral oils or, in particular, hydrocarbons of the boiling rangeof middle oils which are obtained by the reduction of carbon monoxide,as

vwell as middle oils obtained by the destructive oxide or most suitablyon active alumina. Natural or artificial aluminum and/or magnesiumsilicates, which may he provided with a metal oxide, especially one ofthose named alcove, may also be employed.

The partial pressure or" the hydrogen advantageously amounts to aboutfrom 25 to 35 per cent oi the total pressure which may range from about3 to about 25, more particularly from 5 to it atmospheres. if too largeamounts of undesired gases, especially gaseous hydrocarbons, as forexample methane, should collect in the gases returned to the reactionspace, these may be removed, either wholly or partly, example bywashing. For this purpose, from the gases leaving the reaction space,part may he branched oil and purified and the resulting hydrogenreturned to the reaction space, either alone or in conjunction withunpuri'fied gas, Fresh hydrogen is required merely the outset or theoperation,

but nothing is added during the operation; there is no need, therefore,of means for the preparation of hydrogen.

In contrast to the destructive hydrogenation. the process according tothe present invention naturally requires the catalysts to be reactivatedfrom time to time: however, the desired operation may last considerablylonger than when working in the absence of hydrogen, for instance it maylast for at least 2 hours, generally from 4 to 20 hours and may evenlast for substantially longer periods of, for example, several days. Itmay be of advantage to pass the gas containing hydrogen which isreturned to the reaction space for some time over the catalyst at thereaction temperature without an addition of initial material, wherebythe catalyst is reactivated in part and the requirement of a completereactivation further put oil.

The reactivation is accomplished in known manner by means of gasescontaining oxygen, the

vated temperature and, if desired, under pressure. The catalystsmentioned above may be reactivated many times.

The hydrocarbon oils obtained by a single pass through the reactionchamber consist to the A paraiflnic middle oil obtained by thehydrocarbon synthesis from carbon monoxide and hydrogen, having aboiling range from 200 to 335 C. and an aniline point of 87 0., ispassed over a catalyst consisting of active alumina with 6 per cent ofmolybdenum trioxide under a total pressure of 25 atmospheres, togetherwith 0.6 cubic meter of circulation gas. The hydrogen partial pressureis about 40 per cent of the total pressure and the reaction temperatureis 510 C. The catalyst, which is used in the form of pieces, is slowlypassed through the reaction chamber in the same direction as the gasesand vapors, so that its time of sojourn in the reaction vessel is about14 hours. The catalyst, withdrawn from the catalyst chamber, isreactivated by oxidation with air at temperatures not exceeding '70 0.and used again.

Besides 16.5 per cent of gaseous hydrocarbons, a liquid product isobtained containing 44 per cent of gasoline and 56 per cent of middleoil. The gasoline has an octane number of 64 and contains per cent ofconstituents boiling up to 100 C. It contains 29 per cent of aromatichydrocarbons and only 1.5 per cent of olefines. The middle oil boilsbetween 200 and 343 C. and is strongly aromatized as compared with theinitial material, which fact is evidenced by its aniline point of C.

What we claim is:

In a process for the production of knockresistant motor fuels fromhydrocarbon oils by catalytic vapor phase cracking at elevatedtemperatures and pressures in the presence of hydrogen and recycling ofhydrogen-containing reacted gases, the improvement which comprises usingin combination an aliphatic starting material boiling mainly within theboiling range of middle oils, an oxide of a metal selected from the 2ndto the 6th group of the periodic system as the catalyst, a temperatureof 420-560 C., a total pressure of 3-25 atmospheres, a hydrogen partialpressure of 25% to of the total pressure and a gas recycle ratio of0.3-2 cubic meters per kilogram of starting material, partlyreactivating the catalyst by passing the hydrogen-containing recycle gasover the catalyst at the cracking temperature without the addition ofinitial material and completely reactivating the catalyst after areaction time of at least two hours.

MA'I'HIAS PIER. ERNST DONATH.

